1. Field of the Invention
The present invention relates generally to cotton harvester spindles and, more specifically, to a spindle nut and bushing assembly.
2. Related Art
Cotton pickers typically include from two to five forwardly located row units, each unit supporting a pair of upright picker drums having from twelve to sixteen picker bars. Each picker bar, in turn, rotatably supports up to twenty picker spindles. A total of up to 320 spindles are therefore supported from each drum. A large amount of mass is put in motion when the picker drums are rotated. The row units are relatively heavy and their weight shifts center of gravity of the harvester forwardly.
Each spindle is supported in a picker bar by an assembly including a threaded metal nut having a cylindrically shaped bore and a two-piece metal bushing pressed into opposite ends of the bore. The spindle is inserted into the two-piece bushing and a dust collar is placed over the spindle adjacent the outer end of the nut. The opposite end of the nut is then threaded into the picker bar so that a spindle bevel gear meshes with a similar bevel gear on a drive shaft which extends through the bar. Such a spindle assembly is shown, for example, in U.S. Pat. No. 4,757,671 which is of common ownership with the present invention.
The nut and bushing assembly adds considerable weight to the unit. The nut alone accounts for over 47 kilograms per two-drum row unit. The two-piece pressed bushing has been necessary in the past designs to provide a lubricant cavity between the bushing components and to limit the bushing outer diameter to length ratio. However, such a two-piece design presents opportunity for bushing misalignment, increases the number of parts, and results in a less than optimum coefficient of friction.
To minimize spindle bar damage on impact, the spindle is designed to break off near the end of the spindle nut if a large force at an angle to the spindle axis is encountered, for example, if the spindle hits a rock or post or the like. The nut must remain intact for proper spindle breaking action.